In order to meet ever-increasing demands for higher information bandwidth, state-of-the-art digital communication switches, servers, and routers often use multiple rows of optical transceiver modules arranged in very close proximity to one another to increase module density. To be a commercially fungible product, the optical transceiver modules generally need to have basic dimensions and mechanical functionality that conform to an industry standard Multi-Source Agreement (MSA). Of course, many optical transceiver module designs that comply with and add value beyond the basic mechanical functionally set forth in the MSA are possible.
One known optical transceiver module design that complies with such an MSA is the Quad Small Form-Factor Pluggable (QSFP) optical transceiver module. QSFP optical transceiver modules are designed to mate with an opening formed in a cage. The module housing has one or more receptacles configured to mate with one or more respective optical connectors that terminate ends of respective optical fiber cables. The most common type of optical connector used with QSFP optical transceiver modules is called the LC optical connector.
When a QSFP or similar type of optical transceiver module is in a stored position inside of a cage, catches formed in opposite sides of the module housing engage respective latches formed in opposite sides of the cage to prevent the module housing from inadvertently coming out of the cage opening. Module housings of this type typically include a pair of cage latch stops formed on opposite outer side walls of the module housing that engage the pair of latches formed on opposite side walls of the cage to secure the module housing to the cage when the module housing is fully inserted into the cage.
With these types of module designs, a delatching mechanism is mechanically coupled to the module housing and is operable to delatch, or disengage, the latch stops of the module housing from the latches of the cage to allow the module to be extracted from the cage. The delatching mechanism includes a pair of slider arms that are linearly movable along the opposite outer side walls of the module housing and a bail that is rotatable by a user to allow it to be moved from a latched position to a delatched position. The bail is mechanically coupled to a yoke that is joined with proximal ends of the slider arms. The distal ends of the slider arms have respective hook features formed thereon that curve outwardly away from the respective outer side walls of the module housing.
When the module housing is fully inserted into the cage, the slider arms are positioned in between the respective outer side walls of the module housing and the respective inner side walls of the cage. Rotation of the bail to the delatched position pulls the slider arms along the respective outer side walls of the module housing in the direction toward the cage opening. As the slider arms move in this direction, the hook features on the distal ends of the arms press outwardly against the respective cage latches formed on the inner side walls of the cage, thereby causing the cage latches to disengage the respective cage latch stops formed in the opposite outer side walls of the module housing. The user then uses the bail as a handle to pull the module from the cage.
FIG. 1 illustrates a top perspective view of a known QSFP optical transceiver module 2 equipped with such a delatching mechanism 3 mechanically coupled with the module housing 2a. In FIG. 1, the bail 3a of the delatching mechanism 3 is in the latched position. FIG. 2 illustrates a side plan view of the QSFP optical transceiver module 2 shown in FIG. 1 with the bail 3a of the delatching mechanism 3 in the latched position. FIG. 3 illustrates a side plan view of the QSFP optical transceiver module 2 shown in FIG. 1 with the bail 3a of the delatching mechanism 3 in the delatched position.
The delatching mechanism 3 also includes slider arms 3b and 3c and a yoke 3d, which is joined with proximal ends of the slider arms 3b and 3c. In FIG. 1, only one of the slider arms 3b is visible, and in FIGS. 2 and 3, only the other slider arm 3c is visible. The bail 3a is mechanically coupled to the yoke 3d via a cam/cam follower arrangement that will be described below in more detail. The yoke 3d is movable in the forward and rearward directions represented by arrows 5 and 6, respectively. A spring (not shown) of the delatching mechanism 3 continuously exerts a force on the yoke 3d in the rearward direction represented by arrow 6 such that when there is no force or a smaller force exerted on the yoke 3d in the forward direction represented by arrow 5, the yoke 3d returns to its rearward position shown in FIGS. 1 and 2.
Two press-fit pins 7 pass through respective holes (not shown) formed in opposite sides of the bail 3a, through respective slots (not shown) formed in opposite sides of the yoke 3d, and are press fit into respective blind holes (not shown) formed in opposite sides of the module housing 2a. The press-fit pins 7 rotationally couple the bail 3a to the module housing 2a. The bail 3a has cams 8 disposed on opposite sides thereof that engage cam followers 9 disposed on opposite sides of the yoke 3d when the bail 3a is rotated from the latched position shown in FIGS. 1 and 2 to the delatched position shown in FIG. 3. The engagement of the cams 8 with the cam followers 9 from the time of initial engagement until the bail 3a has been fully rotated to the delatched position shown in FIG. 3 pulls the yoke 3d in the forward direction represented by arrow 5. Movement of the yoke 3d in this direction results in movement of the slider arms 3b and 3c in the same direction. This movement of the slider arms 3b and 3c causes hook features 3e and 3f disposed on distal ends of the slider arms 3b and 3c, respectively, to move from their rearward positions shown in FIG. 2 to their forward positions shown in FIG. 3.
When the module 2 is inside of a cage (not shown), the movement of the hook features 3e and 3f from their rearward positions to their forward positions causes them to press outwardly against the aforementioned cage latches formed on the inner side walls of the cage, thereby causing the cage latches to disengage respective cage latch stops 2b (FIG. 1) and 2c (FIGS. 2 and 3) formed in the opposite outer side walls of the module housing 2a. The user may then use the bail 3a as a handle to pull the module 2 from the cage.
Typically, the cams 8 of the bail 8a do not make contact with the cam followers 9 until the bail 3a has been rotated from the latched position shown in FIGS. 1 and 2 by an angle of about 80°, i.e., the delatching mechanism 3 has a passive stroke of about 80°. Once the cams 8 make contact with the cam followers 9, further rotation of the bail 3a by an angle of about 90° or slightly greater from the latched position places the bail in the delatched position shown in FIG. 3. Once the bail 3a has been rotated to the delatched position, a user typically uses a thumb (not shown) placed on the upper side of the bail 3a and a finger (not shown) placed on the lower side of the bail 3a to grip the bail 3a and pull the module 2 from the cage.
One of the disadvantage of the known delatching mechanism 3 described above with reference to FIGS. 1-3 is that there must be space below the bail 3a when it is in the delatched position for the user's finger to grip the lower side of the bail 3a in order to extract the module 2 from the cage. For this reason, when storing multiple modules 2 in cages one above the other in close proximity to one another, the modules 2 must be spaced apart to provide space for the user to grip the bails 3a. This reduces module mounting density, which can lead to reduced bandwidth due to spatial constraints. In addition, storing the modules 2 in this way is a poor solution in terms of ergonomics in that it makes it difficult or impossible for a user to delatch and extract the modules 2. Also, for modules 2 that are stored in cages closer to the ground, it is difficult for a user to properly grip the bail 3a with a finger and thumb and use the bail 3a as a handle to extract the module 2 from the cage when the bail 3a is in the delatched position.
Another disadvantage of the known delatching mechanism 3 described above with reference to FIGS. 1-3 is that there is nothing to prevent a user from plugging an optical LC connector (not shown) into one of the receptacles 11 when the module 2 is in the delatched state shown in FIG. 3. With modules having the design shown in FIGS. 1-3, the LC connector should only be mated with the receptacle 11 when the module is in the latched state shown in FIGS. 1 and 2. If the LC connector is mated with the receptacle 11 when the module is in the delatched state shown in FIG. 3, the bail 3a will not be able to be rotated into the latched position that it needs to be in to latch the module housing 2a with the cage. However, because there is nothing to prevent an LC connector from being mated with the receptacle 11 when the module 2 is in the delatched state, the design is prone to human error and therefore improper installment can occur.
A need exists for a delatching mechanism that allows module mounting density to be increased while also providing an ergonomic solution that allows the modules to be easily delatched and extracted from their cages.